For most calibrations to ahve any value, they need to be traceable to a national lab such as NIST (US), NPL (UK), or NRC (Canada). National lbas provide uncertaintly and confidence levels for equipment they calibrate. The equipment calibrated at a national las isusually a transfer standard that is then used to calibrate. equipment in a working lab.

As long the sensors are analog, and the component values get affected by the ambient conditions , there will be need for calibration. However the reference equipment itself is subject to periodic calibration for which some absolute reference standards are required in the test and measurement lab.

Many people believe that modern digital equipment makes the need for calibration obsolete. They are wrong. I recently found a "currently calibrated" digital (long stem) thermometers that was reading 24.0 °F high, a digital logging thermometer that required a 13.0 °F offset to read correctly, and a digital scale that was reading 25 pounds off (on a 75 pound scale). If your team starts questioning instrument calibrations, push back. If the measurement is worth making, it is worth making it correctly.

@Caleb, There is another issue relating to NASA and the military regarding calibration. These organizations have their own promary standards and calibratin procedures. There is debate in the calibration community about NIST traceability and is it necessary in some circumstances. In other words, should one accept measurement that may not be NIST traceable?